1. Field
The present invention relates generally to emergency broadcasting and, more particularly, to methods and apparatus for sending emergency broadcast information to remote terminals.
2. Background
Communication systems may use a single carrier frequency or multiple carrier frequencies. Generally in wireless communication systems, a channel consists of a forward link (FL) for transmissions from an access network (AN) to an access terminal (AT) and a reverse link (RL) for transmissions from the access terminal (AT) to the access network (AN). The access terminal (AT) is also commonly known as a remote station, a mobile station or a subscriber station and may be mobile or stationary. Each forward or reverse link may incorporate a different number of carrier frequencies.
Modern communications systems are designed to allow multiple users to access a common communications medium. Numerous multiple-access techniques are known in the art, such as time division multiple-access (TDMA), frequency division multiple-access (FDMA), space division multiple-access, polarization division multiple-access, code division multiple-access (CDMA), and other similar multi-access techniques. The multiple-access concept is a channel allocation methodology that allows multiple user access to a common communications link. The channel allocations can take on various forms depending on the specific multi-access technique. By way of example, in FDMA systems, the total frequency spectrum is divided into a number of smaller sub-bands and each user is given its own sub-band to access the communications link. Alternatively, in TDMA systems, each user is given the entire frequency spectrum during periodically recurring time slots. In CDMA systems, each user is given the entire frequency spectrum for all of the time but distinguishes its transmission through the use of a code.
Communication systems have also incorporated broadcast services. For example, Broadcast-multicast services (BCMCS) provide point-to-multipoint communication service in a wireless communication system to a plurality of subscriber stations that receive broadcast data through a wireless communication medium. The broadcast data (i.e., content) transmitted by the wireless communication system to the plurality of subscriber stations may include, but need not necessarily be limited to, news, movies, sporting events, and the like. The specific type of content transmitted to the subscriber stations may include a wide array of multi-media data, such as text, audio, picture, streaming video, etc. The content is typically generated by a content provider and is broadcast to the subscriber stations that subscribe to the particular service over a broadcast channel of the wireless communication system.
As subscriber stations have become far more functional than providing mere one-to-one voice communication, there is a need to provide broadcast notifications, such as emergency information, to subscribers. While emergency notifications may require a finite amount of resources, there is a need to provide an emergency notification service that does not consume significant power in order to vigilantly monitor for emergency notifications.